The development of dynamical mean field theory, first in its single-site form, then its extension to clusters, and finally its interface with band theory, has led to new insights into the basic question of the interaction-driven (``Mott'') metal-insulator transition. In this talk I will review the method, summarizing what has been done and can be done, and presenting new results on metal-insulator transitions in high-transition temperature cuprates, rare-earth nickelates and other materials. The new results show that the classical Mott picture of local ``Coulomb blockade'' does not account for crucial aspects of the observed behavior of many materials. In the cuprate context, intersite correlations, which can now be treated by cluster dynamical mean field methods, show that the metal insulator transition is multistage, with the insulator separated from the fermi liquid metal by a pseudogap regime with a nontrivial interplay with superconductivity, while in the nickelates a new ``site selective'' Mott mechanism has been uncovered. This work was performed in collaboration with E. Gull, P. Werner, O. Parcollet and C. Marianetti and is supported by the US National Science Foundation under grant DMR-1006282 and the US Army Research Office under contract 56032-PH.